Evaluation Of Commercial Pervaporation Membranes For Desalination Of Saline And Brackish Waters

Pervaporation is a solution separation method that occurs by vapor transport through a selective membrane. As the need to provide drinking water to the growing population increases, pervaporation has potential merit as an alternative desalination technology, especially for water with very high salinity. To our knowledge, there are no commercially available pervaporation membranes made specifically for desalination applications. Thus, the membranes PERVAP 4100 and PERVAP 4101 manufactured by DeltaMemAG were tested to evaluate their performance in desalination. Because the driving force in pervaporation is the difference in vapor pressure between the feed side and the permeate side of the membrane, the commercial membranes were tested with feed temperatures of 40°, 60°, and 80°C and with a constant permeate temperature of 5°C. Aqueous sodium chloride feed solutions were tested with nominal mass fractions of 0.6%, 3%, 6% with conductivities of 10, 50 and 100 mS/cm at 25°C, respectively. In total, 18 experiments were performed (nine experiments per membrane). For each experiment, permeate mass and conductivity were measured, and flux, rejection, and recovery were calculated. For all experiments, the conductivity reduction exceeded 97.5%, and 11 of the 18 experiments resulted in conductivity reduction greater than 99.7%. Salinity removal was not observed to be correlated with feed temperature or feed salinity. Flux ranged from approximately 0.03 kg m-2 hr -1 to 9.79 kg m 2 hr 1 and was positively correlated with feed temperature and negatively correlated with feed salinity. Based on these results research is needed to optimize the fabrication of pervaporation membranes for desalination purposes. Specifically, pervaporation desalination could be more competitive by increasing the water flux